Synthesis and antiproliferative activity of novobiocin analogues as potential hsp90 inhibitors.

A series of substituted coumarins1-10 was designed and synthesized as a novel class of 4TCNA analogues. Compound 2a showed excellent antiproliferative activity with mean GI50 values at a micromolar level in a diverse set of human cancer cells (GI50 = 2-30 µM) and induced a high apoptosis level in MCF-7 breast cancer cell line. The molecular signature of hsp90 inhibition was assessed by depletion of the Erα hsp90 client protein.

Discovery and biological activity of 6BrCaQ as an inhibitor of the Hsp90 protein folding machinery.

Heat shock protein 90 (Hsp90) is a significant target in the development of rational cancer therapy, due to its role at the crossroads of multiple signaling pathways associated with cell proliferation and viability. Here, a novel series of Hsp90 inhibitors containing a quinolein-2-one scaffold was synthesized and evaluated in cell proliferation assays. Results from these structure-activity relationships studies enabled identification of the simplified 3-aminoquinolein-2-one analogue 2 b (6BrCaQ), which manifests micromolar activity against a panel of cancer cell lines. The molecular signature of Hsp90 inhibition was assessed by depletion of standard known Hsp90 client proteins. Finally, processing and activation of caspases 7, 8, and 9, and the subsequent cleavage of PARP by 6BrCaQ, suggest stimulation of apoptosis through both extrinsic and intrinsic pathways.